1. Field
The present disclosure relates generally to testing components and, in particular, to testing composite components for inconsistencies. Still more particularly, the present disclosure provides a method and apparatus for identifying wrinkles in composite components.
2. Background
Aircraft are being designed and manufactured with greater and greater percentages of composite materials. Some aircraft may have more than 50 percent of their primary structure made from composite materials. Composite materials are used in aircraft to decrease the weight of the aircraft. This decreased weight improves performance features, such as payload capacities and fuel efficiencies. Further, composite materials provide longer service life for various components in an aircraft.
Composite materials are tough, light-weight materials created by combining two or more dissimilar components. For example, a composite may include fibers and resins. The fibers may be in the form of a substrate or matrix. For example, the fibers may take the form of a woven cloth. The resin may form a reinforcement for the substrate. The fibers and resins are combined and cured to form a composite material.
Composite materials are used in components, such as, for example, without limitation, support beams, frames, and stiffeners for aircraft or other vehicles in which reduced weight, increased strength, and improved corrosion and fatigue resistance is desired. Such components may be formed by laying up plies of composite materials to form a structure for the desired components and then cured with a resin infused in the layers of plies. The plies may be, for example, unidirectional carbon fiber composite materials.
Inconsistencies may occur during the manufacturing of the components. For example, some of the plies may wrinkle during the fabrication of certain components. In particular, components having a curved configuration or having non-uniform cross sections along the length of the component may have wrinkles. Such wrinkles are often undesirable, because the wrinkles may result in a reduction in performance of the component.
Ultrasonic signals have been used to identify inconsistencies in composite components. For example, pulse echo (PE) and through transmission ultrasonic (TTU) methods are currently used to detect wrinkles in composite components. X-rays also have been used to detect inconsistencies in composite components. X-rays are sensitive to changes in the composite laminate caused by inconsistencies, such as wrinkles.
The identification of a wrinkle includes more than detecting the presence of a wrinkle. The presence of a wrinkle may not affect the performance of the component such that reworking or replacement of the component is needed. The dimensions of the wrinkle are used to determine whether actions are to be taken.
As a result in nondestructive testing of components, the identification also may include measuring dimensions for the wrinkle. Ultrasonic nondestructive evaluation procedures can be sensitive enough to identify dimensions of plies in composite laminates if the frequency is sufficiently high.
In the case where a wrinkle is detected but cannot be measured, the component may be reworked or discarded. This result may occur even if the wrinkle does not affect the performance of the component. The inability to measure the dimensions of the wrinkle, however, may result in increased costs and time to rework the component or to manufacture another component as a replacement.
Therefore, it would be advantageous to have an apparatus and method that takes into account one or more of the issues discussed above, as well as possibly other issues.